In order to improve the running times and non-productive times, the axis speeds and the axis accelerations of the machine parts of machine tools are constantly increased. This results in major frictional losses in driving and guiding elements and in an increased heating of certain machine areas. In order to reduce these problems, encapsulated and cooled drive motors for the respectively moving machine parts have been used. The thermal encapsulation of the drive motors can lead to the fact that in particular in the case of highly dynamic machines more heat is introduced into the machine structure by friction in the linear guides rather than by the drives as such. The heat is introduced into the slides via the guiding shoes at a defined location and, if necessary, can be measured by a fixedly attached temperature sensor and therefore the effects of the heat input on the machine can be linearly compensated. On the other hand, the heat input into the machine structure takes place via the guiding rails in a way as a “line load,” this thermal line load, that is, also the local distribution of the heat input in the respective machine part over the driven distance, depending on a number of parameters and on the NC program. Since the heat input changes with the location, it is no longer possible to detect and analyze it with stationary temperature sensors. This applies in particular to the cases in which only short machining is carried out with small lifting distances in rapid sequence on one or more workpieces. The disadvantageous result is heating and thus thermal deformations of the guiding rails, said deformations impairing the machining accuracy and reducing the life-time of the guiding systems due to increased wear.
According to patent publications EP 1 785 225 A and JP 2002 266977, the prior art includes spindle drives for machine tool components that have internal cooling for lowering the temperature of the spindle over its entire effective length and for avoiding heat concentrations in particularly stressed lengthwise sections. For the purpose of cooling, two longitudinal channels are formed in the spindle interior, those channels being connected to each other at one end and being provided with connections for supplying and discharging cooling liquid at the other end thereof. Due to the rotation of the spindle it is necessary to use multi-sealed rotating connections for the pressurized cooling liquid, which requires a technical input along with relatively high costs. There are no effects on the thermal behavior of the guiding system of the machine parts moved by the linear drives.
German patent DE 10 2005 029 854 B4 discloses a guiding rail for a linear guiding system which is designed for being used in machine tools. The respective guiding rail has internal cooling by means of a cooling liquid. Instead of having an inner longitudinal bore to be produced with technical input, a longitudinal groove is formed in the bottom of this known guiding rail, the groove being filled with cooling liquid. However, the leakages of the cooling liquid, occurring in the long-term operation when the mechanical and/or thermal loads are high, are problematic.